This invention relates to a device for measuring blood pressure and in particular to such a device which requires very a short time duration for measurement.
Generally, a device for measuring blood pressure, making use of a pressure cuff, is based on the processes of pressurizing a pressure cuff until the artery is completely closed, gradually evacuating the cuff (gradual evacuation) thereafter, and determining systolic pressure and /or diastolic pressure according to the detection of the Korotkoff sound (K sound) and its disappearance, or detecting pulsatile waves during the evacuation of the pressure cuff and obtaining the systolic pressure and /or the diastolic pressure from the point where rate of the increase and /or the decrease of the amplitude of the pulsatile wave increases and /or decreases, as the case may be.
Therefore, according to such devices for measuring blood pressure, the pressure cuff must be pressurized slightly over the systolic pressure (systolic pressure +.alpha.) and subsequently evacuated until the pressure cuff pressure drops slightly below the diastolic pressure (diastolic pressure -.beta.), and, therefore, the time duration required for measuring blood pressure was undesirably long. As a result, not only the time is wasted for measuring blood pressure, but also considerable pain was caused to the patient because of the pressure applied to his arm for a fairly long time duration, and it could even be hazardous for the patient if his physical condition is extremely grave. An additional disadvantage of the conventional devices was that possible congestion of blood may become a cause of measuring errors.